The aim of this grant is to understand human allergic disease processes and, in so doing, to develop new means of therapy. The in vitro portion of this work focuses on purified human basophils and mast cells, the latter obtained from lung and intestine. We seek to understand the biochemical mechanisms by which histamine and other mediators are released after antigen or a-IgE challenge. The studies involve measurements of arachidonic acid metabolism and cyclic nucleotide levels in stimulated cells with the aim of linking these metabolic events with mediator release both kinetically and by studies with appropriate pharmacologic inhibitors. Other nonimmune, but biologically relevant, stimuli (e.g., f-met peptides, C5a, hyperosmolarity) also release mediators and the mechanisms of release by these agents will be pursued. We shall develop morphologic evidence relating to the mechanisms of degranulation at the EM level. We are interested in defining the full panoply of mast cell and basophil mediators, including arachidonic acid metabolites (LTC, PGD, 5HETE, etc.), AGEPC, as yet undefined chemotactic factors, proteoglycans, and the proteolytic enzymes capable of generating biologically active substances such as kinins. We shall study the importance, for allergic phenomena, of basophil and mast cell interactions with eosinophils, platelets and macrophages, each of which has variably well-defined factors which cause mediator release. We have observed that certain individuals have basophils which are hyperresponsive to certain stimuli; this is often the case with cells from atopics and usually the case with asthmatic individuals. We plan studies to understand the nature of this increased "releasability" and its relationship to clinical disease. The in vivo aspects of this project involve nasal antigen challenge of sensitive individauls in the correlation of clinical symptoms with measurement of mediators released in vivo immediately after challenge and during the late phase reaction. We shall also study nonimmunologic stimuli in this system, focusing on release by cold, dry air, a model for the airways response which is linked to exercise-induced asthma. Finally, we will study standard and novel drugs to ascertain the relevance of in vitro inhibition of mediator release to the in vivo results. By understanding the patterns of mediator release and the mechanisms by which it occurs with IgE-related and other stimuli, we feel that clinically useful pharmacologic intervention in asthma and other allergic diseases will become possible.